This document discusses Java 8 features including Optional, lambdas, and Stream API. It provides advice on properly using Optional to avoid null checks, keeping lambda expressions simple, and only using streams for functional-style operations without side effects. The document recommends using method references when possible and external libraries like jOOL and StreamEx that extend the stream functionality. It concludes by providing contact information for the authors to ask additional questions.

1. Java 8: The Good, the
Bad and the Ugly
Mikalai Alimenkou
@xpinjection
Oleg Tsal-Tsalko
@tsaltsol

2. LEAD SOFTWARE ENGINEER AT EPAM SYSTEMS.
PASSIONATE DEVELOPER, SPEAKER, ACTIVE
MEMBER OF KIEV JUG.
PARTICIPATE IN DIFFERENT EDUCATIONAL
INITIATIVES, ENGINEERING EVENTS AND
JCP/ADOPTJSR PROGRAMS.
MEMBER OF ARCHITECTURE EXCELLENCE
INITIATIVE AND ENGINEERING PRODUCTIVITY
GROUPS IN EPAM.
OLEG TSAL-TSALKO

5. Disclaimer
This talk is based on
personal experience

7. You could follow code samples
https://github.com/xpinjection/java8-misuses

8. #1. Optional

10. Wrap nullable values
in Optional to operate
on them
Use chained
methods
Optional containers
should be short lived
Carefully choose
what to wrap

11. #2. Lambdas

13. Avoid long or complex
lambda expressions
Prefer reusable
method references
Be concrete with
functional interfaces
Use specific
methods on
collections

14. #3. Stream API

16. Don’t mix streams and
imperative code
Avoid complex
nested streams
Don’t use external state
with streams
Take a look at
extensions like
jOOL, StreamEx.

17. And remember…

18. @tsaltsol
oleg.tsalko@gmail.com
@xpinjection
mikalai.alimenkou@xpinjection.com